MEXICO CITY (Reuters) - The leading candidate for Mexico’s presidential election, Andres Manuel Lopez Obrador, reiterated on Thursday his pledge to review oil contracts if elected, a day after the most successful auction since a landmark energy opening was finalized in 2014.

Royal Dutch Shell Plc snapped up nine of 19 Gulf of Mexico oil and gas blocks awarded in the auction on Wednesday, as Mexico offered foreign energy firms the right to drill beneath prized deep waters that may contain billions of barrels of oil.

“We’re going to review the contracts,” said Lopez Obrador, who is leading opinion polls five months before the July vote.

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Mexican officials estimated the auction could bring $93 billion in investment to the country as oil firms develop the areas they won.

The stakes were high for Mexican President Enrique Pena Nieto and his struggling party, which wants to showcase the results of its energy liberalization ahead of the presidential election.

Lopez Obrador said that Wednesday’s auction “is just a show, pure demagoguery.”

Along with other officials of his leftist MORENA party, Lopez Obrador has in the past called for a public referendum on the liberalization as well as the need to review signed contracts.

“The contracts that were signed are, more than anything else, for financial speculation, not for production, not to extract oil, not to develop the oil industry.”